Charge pump circuit
View Patent ↗In a charge pump circuit provided with a positive electric potential generating charge pump circuit that generates a positive electric potential and a negative electric potential generating charge pump circuit that generates a negative electric potential, a parasitic bipolar transistor is prevented from turning on so that the charge pump circuit performs normal voltage boosting operation. First, the negative electric potential generating charge pump circuit is put into operation to generate −VDD as an output electric potential LV. Since the output electric potential LV is applied to a P-type semiconductor substrate, an electric potential of the P-type semiconductor substrate becomes −VDD. After that, the positive electric potential generating charge pump circuit is put into operation while the negative electric potential generating charge pump circuit continues its operation. The positive electric potential generating charge pump circuit performs the normal operation, because the electric potential of the P-type semiconductor substrate is −VDD. After the output electric potential HV of the positive electric potential generating charge pump circuit reaches 2VDD, the negative electric potential generating charge pump circuit is put into a second operation mode (inverting HV).
1. A charge pump circuit comprising:
a positive electric potential generating charge pump circuit that generates a positive electric potential;
a negative electric potential generating charge pump circuit that generates a negative electric potential;
a semiconductor substrate of a first general conductivity type to which the negative electric potential is applied;
a control circuit that controls the negative electric potential generating charge pump circuit and the positive electric potential generating charge pump circuit;
a well of a second general conductivity type formed in a first surface portion of the semiconductor substrate, the positive electric potential being applied to the well; and
a diffusion layer of the second general conductivity type formed in a second surface portion of the semiconductor substrate,
wherein the control circuit controls the positive and negative electric potential generating charge pump circuits so that the positive electric potential generating charge pump circuit starts generating the positive electric potential after the negative electric potential generating charge pump circuit starts generating the negative electric potential.
2. The charge pump circuit of claim 1 , wherein the negative electric potential generating charge pump circuit is configured to generate the negative electric potential using the positive electric potential generated by the positive electric potential generating charge pump circuit.
3. The charge pump circuit of claim 2 , wherein the negative electric potential generating charge pump circuit generates the negative electric potential by inverting the positive electric potential.